Graduate Program Events |
Events on Monday, July 7th, 2025
- Cross Correlation of IceCube Neutrinos with Tracers of Large Scale Structure
- Time: 11:00 am - 1:00 pm
- Place: 5280 CH
- Speaker: David Guevel, Physics PhD Graduate Student
- Abstract: Multi-messenger astrophysics aims to study energetic astrophysical environments using physical channels that have historically been inaccessible. Technological developments have created new opportunities to detect neutrinos, cosmic rays, and gravitational waves from distant astrophysical environments. Neutrinos are unique among these messengers because they are produced in large numbers in energetic environments and because they propagate through interstellar and intergalactic space with little interaction along the way preserving the information about their sources. The IceCube Neutrino Observatory has discovered astrophysical neutrinos from extragalactic, and galactic sources and unresolved background sources. The accelerators that produce the energetic extragalactic neutrinos likely trace the large-scale structure, so the diffuse astrophysical neutrino flux may exhibit anisotropy similar to other large-scale structure tracers though no anisotropy has been detected in the diffuse neutrino flux. Galaxies, detected in infrared observations, are well-suited to be used as tracers of large-scale structure. This thesis presents a two-point angular cross-correlation between IceCube neutrinos and an infrared galaxy catalog. This angular correlation required novel modifications to include the effects IceCube's declination and energy dependent effective area and point spread function while also accounting for multipole coupling caused by the use of a galactic plane mask. Despite improvements in the sensitivity to anisotropy, no statistically significant correlation was observed. The upper limit on the correlation strength is used to place constraints on the share of the diffuse neutrino flux that can be contributed from source correlated with the local large-scale structure. If the neutrino spectral energy distribution follows a power law with a spectral index held fixed to the diffuse muon neutrino measurement, the correlated sources can contribute no more than 54% of the diffuse muon neutrino flux. The correlation upper limit rules out nearby source populations while allowing more distant evolution models, such as those tracing the star-formation rate. The next generation of ice Cherenkov detectors such as IceCube Gen2 will be capable of constraining the correlation with three times the precision and potentially detecting anisotropy in the diffuse neutrino flux.
- Host: Ke Fang